1. Field of the Invention
The present invention relates to an LED lamp provided with a motion sensor unit.
2. Description of the Related Art
FIG. 16 shows a conventional LED lamp (see Patent Document 1 for example). The illustrated LED lamp 900, which can be used as an alternative to a traditional straight-tube fluorescent lamp, includes a plurality of LED (Light Emitting Diode) chips 91. The LED chips 91 are encased in a cylindrical translucent cover 94. The translucent cover 94 allows the light from the LED chips 91 to pass through while also diffusing the light. The translucent cover 94 is provided with a pair of caps 92 at its respective ends. With the caps 92 connected to an unillustrated light fixture, commercial electric power of, e.g. 100 VAC (AC voltage), is supplied to the LED lamp 900. The LED lamp 900 includes a power unit (not illustrated) which converts the 100 VAC into DC power for the LED chips 91 to turn on. The LED lamp 900 also includes a motion sensor unit 93. The motion sensor unit 93 senses infrared rays irradiated from e.g. a human body and outputs a detection signal. Upon reception of the detection signal, the power unit performs lighting control, to turn on the LED chips 91 for a predetermined time for example.
However, the motion sensor unit 93, though supposed to sense infrared rays, may also respond to visible light besides infrared rays. Hence, light from the LED chips 91 may be detected by the motion sensor unit 93, thereby causing the LED lamp 900 to operate erroneously even when no moving object is present within the field of view of the sensor.
LEDs are also used as a source of light in lighting equipment such as a focal illuminator (so-called “task light”) and a kitchen illuminator (see Patent Document 2, for example).
Focal illuminators using LEDs have an advantage that their cases can be made thinner than those using incandescent lamps or fluorescent lamps. Such a thin case, however, may be disadvantageous in that it is difficult to provide the case with operational members such as a power switch, a dimmer knob, etc.
Kitchen illuminators often need to be turned on or off with a wet hand, which poses safety risk as well as hygiene risk.
An effective way to handle the above problems may be to introduce a touchless operation system. The touchless operation can be implemented by conventional technique of combining an illuminator with an optical touchless sensor that uses non-contact sensing technology to detect a moving object or an approaching object.
Lighting Apparatus Provided with a Touchless Sensor.
An optical touchless sensor includes a light emitting device such as LED and LD (Laser Diode), and a light receiving element such as phototransistor and photodiode. The light emitting device emits light, so that the light will hit a target of detection and light reflected thereby will be received by the light receiving element, which will then converts the light into an electrical signal to identify a movement and/or position of the target. This method is advantageous in terms of light sensitivity and detection accuracy, and is suitable for proximity sensing, for example.
Touchless sensors can detect the position of a detection target such as a hand of a human operator. Thus, an illuminator with a touchless sensor, for example, can turn On/Off the light in a contactless fashion as the detection target is approaching the predetermined position.
However, with the optical touchless sensors, it is difficult to manufacture products with desired performance at a high yield rate, due to the variation in performance of the light emitting device and the light receiving element, or the variation in mounting accuracy of the components.
Patent Document 4 and Patent Document 5 disclose some examples of conventional optical touchless sensors.